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J, 5%6fifd7Z M y 1964 w. L. SHEPPARD SPEED GOVERNING SYSTEM 11 Sheets-Sheet 11 Filed Dec. 9, 1960 Ill United States Patent 3,133,610 SPEED GQVERNWG SYSTEM William L. Sheppard, 36655 Romulus Sh, Romulus, Mich. Filed Dec. 9, 1960, Ser. No. 74,833 85 Claims. (ill. 180-821) This invention relates to governing systems. This ap plication is a continuation-in-part of my application Serial No. 632,541, filed January 4, 1957, now abandoned. Certain of the subject disclosed herein is claimed in application Serial No. 74,834, filed December 9, 1960, and in divisions hereof and/ or thereof.

An object of this invention is to improve the performances of governor systems.

Another object of this invention is to improve the safety of governing systems by providing for the controlling action to be selectively overridden.

Another object of this invention is to facilitate the adjustment of governing systems, both in the extent of their control and the velocity at which the control will be initiated, and both in initial installation and in use.

Another object of this invention is to reduce hunting in governing systems.

A further object of this invention is to provide a governing system for association with existing vehicles without necessitating any but minor changes in the vehicle and, apart from governing control, without adversely affecting the operation of any part of the vehicle.

Another object of the present invention is to manifest the action of a governing system in the exertion of a force, and to provide means for limiting the maximum magnitude of that force to different values under different conditions.

Another object of this invention is to modulate the forces applied to a speed-controlling linkage in accordance with the speed.

Another object of this invention is to adjust a speed controller to compensate for changes of the controlled speed before they occur.

Another object of this invention is to improve the control of the road speed of the vehicle by developing major compensatory forces in response to changes of road speed and fine compensatory forces in response to changes of a condition indicative of prospective changes of road speed.

A further object of this invention is to anticipate road speed changes of a vehicle before they occur by sensing the changes in the air pressure in the internal combustion engine which must precede the change of engine output torque which precedes the change of road speed.

Another object of this invention is to modulate the force applied to the throttle linkage of an internal combustion engine in accordance with changes of the intake manifold pressure of that engine.

Another object of this invention is to adapt a pneumatic speed controller to perform both semi-automatically and automatically.

A further object of this invention is to automatically control the acceleration of a vehicle.

Another object of this invention is to control the acceleration of a vehicle in accordance with the intake manifold pressure of the internal combustion engine which serves as motive power for the vehicle.

Another object of this invention is to modulatingly change the acceleration of a vehicle in accordance with the deviation between actual road speed and selected road speed over a range of such deviations.

Another object of this invention is to modify the action of a fluid-dynamic force-producing means from one to another flow condition to optimize the means under each of a plurality of conditions.

3,l33,hl Patented May 19, 1964 Another object of this invention is to compensate for regenerative tendencies in a fluid pressure controlling system by developing an opposing degenerative feedback condition.

Certain of the principles of the present invention have been representatively embodied in a governing system for association with an automobile since a number of the features of the invention are particularly advantageous in such use. In general, in one form or mode of operation, control means in the form of a pneumatically operated cylinder is coupled to the accelerator pedal or throttle of the vehicle so as selectively to resist velocityincreasing movement of that pedal, and, under appropriate conditions, to positively exert a force tending to move that pedal in the velocity-decreasing direction. The action of the control means is determined by a valve which responds to a pneumatic pressure difiierential the magnitude of which is established conjointly by a governor driven, representatively, through the vehicles speedometer cable, and by a pressure controlling mechanism connected to the vehicles intake manifold. The road-speed responsive governor may be readily adjusted by the operator of the vehicle through the medium of a knob driving a pointer cooperating with a dial calibrated in terms of road speed. In a modified arrangement disclosed, the system may be operated on a full automatic basis.

The manner of accomplishing the foregoing objects, and other objects of the invention, will be perceived from the following detailed description of embodiments of the invention when read with reference to the accompanying drawings in which:

FIG. 1 is a diagrammatic representation of a velocity governing system shown in association with certain portions of an internal combustion engine vehicle having a speedometer to indicate its velocity of motion;

FIG. 2 is a plan view of the governor illustrated in the system of FIG. 1;

FIG. 3 is an enlarged sectional view taken substantially along the line 3-3 of FIG. 2;

FIG. 4 is a sectional view taken substantially along the line 4-4 of FIG. 3;

FIG. 5 is a plan View, in reduced size, of a spring element employed in the governor illustrated in FIGS. 24 of the drawings at one stage in its construction;

FIG. 6 is a side elevational view of a sub-assembly of the governor illustrated in FIGS. 24 of the drawings, including the spring illustrated in FIG. 5, in the shape which it assumes prior to assembly to the rest of the elements of the governor;

FIG. 7 is a graphical representation of certain pressure versus velocity relationships occurring in one form of conventional governor, as well as certain pressure-velocity relationships occurring in the system of FIG. 1;

FIG. 8 is an enlarged sectional view of the pressure controlling mechanism and control valve illustrated in the system of FIG. 1;

FIG. 9 is a sectional view taken substantially along the line 9-9 of FIG. 8;

FIG. 10 is a sectional view of a modification of the governor of FIG. 1;

FIG. 11 is a sectional view taken substantially along the line 11-11 of FIG. 10;

FIG. 12 is a sectional view taken substantially along the line 12--12 of FIGURE 10;

FIG. 13 is a transverse cross-sectional view of an improved manual controller adapted for association with the governor of FIGS. 1012;

FIG. 14 is a longitudinal cross-sectional view taken substantially along the line 1414 of FIG. 13 and further including a representation of an associated foot brake controlled mechanism and of certain associated electrical circuit elements;

a FIG. 15 is a partially cut-away elevational view of a pressure controlling mechanism and control valve assembly suitable for connection to the manual controller of FIGS. 13 and 14 and to the governor of FIGS. 13.

FKG. 16 is a sectional view of the assembly of FIG. 15 taken substantially along the line 1616 of FIG. 15;

FIG. 17 is a sectional view taken substantially along the line 1717 of FIG. 16.

FIG. 18 is a transverse cross-sectional view of an improved servo adapted for association with the assembly of FIGS. 15-17;

FIG. 19 is a cross-sectional view taken substantially along the line 19-19 of FIG. 18;

FIG. 20 is a cross-sectional view taken substantially along the line 2020 of FIG. 18;

FIG. 21 is a fragmentary cross-sectional view taken substantially along the line 2121 of FIG. 19;

FIG. 22 is a sectional view taken substantially along the line 2222 of FIG. 18;

FIG. 23 is a fragmentary cross-sectional view taken substantially along the line 23-23 of FIG. 18;

FIG. 24 is a view of the linkage at the left of the servo of FIG. 18 as viewed from the left of FIG. 18 and further illustrating the connection of the servo to the throttle linkage and to the carburetor;

FIG. 25 is a graphical representation of the relationship between the air pressure in the governor of FIGS. 10-12 with variations of the road speed of the vehicle with which the governor is associated at one setting of the governor, as well as a graphical representation of the relationship between the pressure in the servo of FIGS. 1824 with variations of the road speed of the vehicle with which the servo was associated under two different conditions of operation;

FIG. 26 is a graphical representation of the relationship between the pressure in the servo of FIGS. 1824 and changes in the pressure in the manifold of the internal combustion engine with which the system is associated;

FIG. 27 is a longitudinal sectional view of a modified form of governor suitable for producing a controlled pressure which is greater than atmospheric and which varies in accordance with the rotational speed of a shaft;

FIG. 28 is a schematic representation of a road speed controlling system in which a source of air at a pressure greater than atmospheric is available; and

FIG. 29 is a graphical representation of certain operational relationships in systems constructed in accordance with certain of the principles of the present invention.

The system illustrated in FIG. 1 of the drawings is representatively so associated with a vehicle as to control the velocity of road speed of that vehicle. The vehicle is assumed to include a dash panel 16 supporting a conventional speedometer 12 adapted to be driven by a flexible, sheathed speedometer cable 314, the speedometer cable being driven by a rotatable element in the transmission train of the automobile so that the speed of rotation of the cable 14 bears a constant relationship to the speed of rotation of the propeller shaft of the automobile and hence reflects road speed.

The vehicle is assumed to be powered by an internal combustion engine including a carburetor 16 having a valve controlled by an arm 13 connected through spring biased linkage 20 to the accelerator pedal or throttle 22 which is depressed by the drivers foot to control the velocity of the vehicle. The carburetor arm 1%, the linkage 20 and the pedal 22 are shown in their normal, released positions so that the carburetor valve is closed and the engine is operating at idle speed. Depression of the throttle 22 will pivot arm 18 in a counter-clockwise direction to open the carburetor valve a selected amount and to accordingly increase the operational speed of the engine. This linkage including accelerator or throttle 22 serves as an operator or driver-operated speed controller for the vehicle or variable speed unit, movable, with respect to the remainder of the vehicle or unit, in engine 3 speed increasing and in engine speed decreasing directions.

It is further assumed that the vehicle is provided with means acting as an air pump to create an air pressure less than one atmosphere and the system of FIG. 1 is illustrated as being connected to a source of reduced air pressure 23 which may be and preferably is the intake manifold of the engine.

The governor or speed responsive means 24, which serves as a fluid-pressure or, specifically, an air-pressure controlling governor, is driven by the speedometer cable 14 in the representatively disclosed arrangement. Since it is customary to provide a detachable connection between the speedometer cable 14 and the speedometer 12, the governor 24 is provided with a fitting 26 adapted to secure the governor 24 to the speedometer 12 and a fitting at the other end adapted to couple to the fitting 23 provided on the speedometer cable 14. Consequently, rotation of the inner flexible member of the speedometer cable 14 produces rotation not only of the movable elements of the speedometer 12 but also of certain movable elements of the governor 24.

Governor 24, to be described in detail hereafter, is employed as a pneumatic pressure controller in the system depicted in FIG. 1. It is provided with two ports one of which is connected to the atmosphere and the other of which, port 30, is connected to a source of reduced air pressure through a mechanism to be described. A valve in the governor interconnects port 30 and the atmosphere to a variable degree determined by the velocity at which the movable elements of the governor are rotated, the degree of that interconnection being also manually settable to permit preselection of the vehicle velocity at which the system will be effective to inhibit further speed increases. This control is exercised through a lever 32 mounted on and rotated about the longitudinal axis of the governor 24 through a limited arc of movement. One end of a balltype chain 34 is secured to the lever 32 and the other end of that chain extends over and is secured on a pulley 36 mounted upon a shaft 38. Shaft 38 is supported by means of a bracket 40 upon the dash panel 10 of the vehicle and carries a knob 42 adapted to be manually rotated by the driver of the vehicle. Knob 42 carries a pointer 44 adapted to cooperate with an illuminated scale 46 calibrated in terms of miles per hour. For example, the shaft 38 may be rotatable through a 160 arc, and the scale 46 may be calibrated, over that are, from 30 miles an hour to miles per hour. In FIG. 1, the equipment is shown in its lowest speed-setting position, rotation of the shaft causing chain 34 to wind upon pulley 36 to move the lever 32 in a direction to increase the speed setting, that is, to increase the road speed of the vehicle at which the "overning system will become effective.

It will be apparent that the governor adjusting shaft could, with appropriate construction of the speedometer, be extended through the speedometer face to drive a 110113181 cooperating with the speedometer indicia if desire Port 30 of governor 24 is connected by means of tube 46 to port 48 of a control valve 50. Valve 50, which serves as a fluid-pressure, or specifically, an air-pressure differential responsive control valve or valve means is provided with a second port 52 connected to an output unit 3t and a third port 54 is connected to a pressure controller 56 which is in turn connected to the source 23.

Control valve 54 includes upper, intermediate and lower chambers 53, 60 and 62, respectively. A flexible diaphragm 64 or air-pressure displaceable element demarks the upper and intermediate chambers 58 and 60, but those two chambers are interconnected by a minute orifice 66 formed in the diaphragm 64. The intermediate chamber 60 communicates with the pressure controller 56 through the port 54 so that the air pressure in chamber 6%) is controlled by pressure controller 56. This pressure is normally appreciably below atmospheric pressure.

Chamber 58 is connected to the governor 24 which controls the pneumatic pressure in chamber 53. During the normal operation of the equipment, air flows from the atmosphere, through the governor, to the chamber 58, through the orifice 66, chamber 60, port 54 and through the pressure controller 56. The governor 24 modulates this pressure flow in accordance with the rotational speed of cable or shaft 14 to modulate the pressure in chamber 58, and in the preferred practise significant changes in the pressure in chamber 58 are accompanied by but very small changes in the rate of flow. Chamber 58 is illustrated as being enlarged to act as a surge chamber to integrate transient pressure variations such as those which might occur, for example, as a result of the unwinding of the speedometer cable 14 during deceleration of the vehicle.

Diaphragm 64 is biased upwardly by a spring 68 and carries a ball '70 cooperating with a valve seat '72 to define a ball valve. In general, at any vehicle velocity below a preselected value or preselected narrow range of values, as selected by the position of knob 42, the pressure ditferential between chambers 58 and 60, as controlled by governor 24, is such that the valve including ball 70 and seat 72 is closed. At vehicle velocities above the preselected value or preselected narrow range of values, the pressure diiferential between chambers 58 and 60 is such that ball 70 tends to be off of valve seat 72, interconnecting chambers 62 and 6%. In operation, ball 70 is controlled so as to modulate the pressure in chamber 62.

Output port 52 of control valve 50 is connected by means of tubing 76 to the input port 78 of a control cylinder or servo d0. "Cylinder 80 comprises a generally tubular casing 82 the closed end of which is apertured to accept the bushing-sealed input-port tube 78. The other end of the casing 82 is closed by means of a filter 8 retained in place upon the casing 82 by means of a crimp ring 86. Filter 84 is centrally apertured to accept a piston rod 3 8 connected to a piston head 90 and is assumed to be sufiiciently rigid to serve as a bearing for that piston rod during its motion. Filter 84 is sufiiciently perforated to permit the maintenance of atmospheric pressure in the cylinder chamber 92 to the left of the piston head 90, but filters the air to prevent the ingress of foreign material into chamber 92. Piston 90 is shown to be backed by a plastic seal 94 and a rigid washer 96 so as to form an airtight junction between the edges of the piston head assembly and the casing 82 so as to prevent air from leaking from the chamber 92, to the left of the piston head, into the cylinder portion 98 to the right of the piston head 90. However, for reasons to be described, a small orifice 100 is formed through the piston head 90 so as to interconnect chambers 92 and 98.

Piston rod 88 is coupled by means of a ball-type chain 102 to the arm 1$ and linkage 20 at the carburetor 16. As will be described in more detail hereinafter, with the control valve 70 closed, there is no eifective pressure differ ential between chambers 92 and 98 in the cylinder 80 and cylinder 30 imposes no effective load resisting the rotation of throttle pedal 22 additional to that of the throttle return spring 104. Under these conditions, the control system will effect no significant change in the operation of the vehicle or in the force which the driver must exert upon the throttle 22 to attain a selected speed. However, at and above the governed speed, as established by the setting of knob 42, the control valve including ball 70 will be open or incipiently open to fully or partially interconnect control-valve chambers 60 and 62, producing a modulated reduction in the air pressure in chamber 9% of the cylinder St). The piston head 90 consequently tends to move to the right in the view of FIGURE 1, tending to so move the arm 18 and linkage 20 that the cars velocity will be reduced unless the driver applies substantial additional force upon the throttle 22 to override this control action. It will therefore be seen that in the disclosed arrangement, servo or pressure actuated motor 80 serves as a fluid-pressure-dilferential responsive actuator means or pressure actuated force producing means.

If desired, a compression spring may be disposed between the piston head and the closed end of casing 82, exerting a small-magnitude force tending to move the piston to the left in the view of FIG. 1.

A form of governor 24 for use in the system of FIG. 1 is shown in FIGS. 2 to 4 of the drawings and is the subject of my copending application, Serial No. 632,470, filed January 4, 1957, now Patent No. 3,064,669, granted November 20, 1962, and an improved form thereof is disclosed in my copending application entitled Governor, filed November 14, 1960, Serial No. 68,877, the disclosure of which is incorporated by reference herein as fully as though completely reproduced herein. Governor 24 comprises a hollow body portion or housing 103 defining an enlarged cavity 110. A section having reduced inner and outer diameters is formed integrally with housing 108 and is externally threaded to define the fitting 28 which is adapted to accept the nut at the end of the conventional speedometer cable assembly. Adjacent the junction between the main body of the housing 1% and the fitting 28, the inner wall of the housing 110 tapers as at 112 and is then recessed to define an annular shoulder 114. The central bore 116 in the fitting portion 28 terminates at the shoulder 114.

A generally tubular extension 118 having a flange 120 is secured to the open end of housing 108 in any suitable fashion such as crimping the edge of the housing 108 over the flange 120 as at 122. The nut 26, adapted to engage the hollow, threaded projecting stud on a conventional speedometer, is secured upon the extension 118 so that relative rotational motion therebetween is prevented. In the adjustment of the unit, the rotational position of the governor 24 is shifted relative to the speedometer, with the governor being then locked in the adjusted position. This is accomplished, in the representative arrangement disclosed, by providing mating threads on the nut 26 and on the extension 118 having a pitch different than the pitch of the threads on the speedometer and the threads mating therewith on the right-hand portion of nut 26. At the present time, male studs on speedometers are customarily formed with sixteen threads per inch and, in one satisfactorily operating arrangement, thirty-two threads per inch were formed on the end of extension 118 and on the left-hand portion of nut 26.

A shaft 124, is disposed axially of the housing 1% and of the extension 118. The central portion of the shaft 124 is circularly cylindrical. The right-hand end of shaft 124-, in the view of FIG. 3, is formed with a square cross section similar to the end of the speedometer cable and this end portion enters and engages movable portions of the speedometer in the same fashion as the end of the speedometer cable normally engages the speedometer. It will be appreciated, of course, that if clips or other end fittings are provided upon the speedometer cable, similar fittings should be provided upon the end of shaft 124.

The left-hand portion 126 of shaft 124 is of greater diameter than the central portion of that shaft, the junction between those portions defining a shoulder 128. End portion 126 is provided with a longitudinal recess a portion 130 of which has a square cross section to define a socket for accepting the end of the speedometer cable. Socket 130 may be formed, for example, by boring and counterboring end portion 126 of shaft 124 and then upsetting the central part of the end portion 126, as shown, to force the central portion of the bar into a square configuration.

The counterbored end of portion 126 is flared outwardly as at 132. over the end of a thrust collar 134 of steel or other similar material. In the disclosed arrangement, thrust collar 134 rotates with shaft 124 relative to fitting 28 and housing 103. The right-hand face of thrust collar 134 abuts a bearing 136 press fitted within the bore 116 in the fitting 28, the right-hand face of bearing 136 3 extending slightly to the right of shoulder 114, as shown. Bearing 136 constitutes the primary supporting means for the shaft 124 although the right-hand end of that shaft is or may be supported by the bearings in the speedometer.

It is important to the operation of the disclosed governor that there be no air leakage past the bearing 136 into the chamber 110, either between the bearing 136 and the wall of the fitting 28 or between the bearing and the surface of the end portion 126 of the shaft 124 which is rotating relative to that bearing. Yet, the provided seal must not offer any substantial resistance to the rotation of shaft 124 since it is important that the governor as a unit require very little torque to produce rotation thereof at the speedometer cable rotational speed, for otherwise the load imposed upon the cable is greater than that for which it is designed and cable breakage or malfunctioning may occur. It has been found that a seal having these characteristics may be achieved by employing a normally planar annular plastic seal deformed from its planar configuration when in position in the unit. Thus, a plastic annulus 140, successfully manufactured of a polytetrafiuoroethylene resin commercially sold under the name Teflon, is disposed in the recess at the end of the cavity 110 and against the shoulder 114. The central aperture in the annulus 140 is smaller than the diameter of the bore 116 and only slightly larger than the outer diameter of the shaft portion 126. A washer 142 made, for example, of steel is positioned against the plastic disc seal 140 and serves to clamp that seal in place, the washer 142 being staked in position, portions of the wall 112 being extruded over the edge of the washer 142 at a plurality of points around the edge of the washer 142 as may best be seen in the sectional view of FIGURE 4. It will be observed that the aperture in the washer 142 is appreciably greater in diameter than the aperture in the seal 140 and greater in diameter than the bore 116 so that it is only the outer edge of the disc 140 which is clamped. Since the bearing 136 projects to the right of the shoulder 114- as previously noted, the central portion of the plastic disc 140 is deflected rightwardly from the plane of the outer edge of that disc. The portion of the disc 140 adjacent the central aperture therein is trapped between the bearing 136 and the shoulder 128 on the shaft 124 so that that inner portion is in a plane different from but parallel with the plane of the outer edge of the disc 140. During the flaring operation at which the lip 132 is established, the shoulder 128 is positioned so that it will be lightly seated against the seal 140. The light seating is necessary to prevent the frictional engagement between the shoulder 142 and the seal 140 from impeding the free rotational motion of the shaft 124.

A sleeve 146 is slideably disposed within the central bore in the extension 118. Under all operative conditions, a portion of this sleeve protrudes to the left of that bore so that a seal 148, seated in a counterbore in the flange 120, continuously engages the surface of the sleeve 146, forming an airtight seal between the outer diameter of the sleeve 146 and the bore in extension 118. The lefthand end of sleeve 146 is counterbored to define an annular shoulder 150 which, as will be seen, serves as a valve seat. The central bore in the sleeve 146 is sufiiciently large to insure that the shaft 124 will not contact that sleeve during its rotation.

As may best be seen in FIGURE 2 of the drawings, the extension 118 is provided with a helical slot 152 extending in the order of 35 to 45 around its circumference. The adjusting lever 32 passes through the helical slot 152 and is secured in a radial aperture in the sleeve 146. One end of a helical return spring 154 engages the lever 32 and the other end is anchored to the housing 108 or the extension 118 in any appropriate manner. For example, the other end of spring 154 may encircle output tube 30 or, alternatively, a radial recess may be formed in element 108 or 118 and the end of the spring 154 inserted therein.

8 The spring 154 exerts a force tending to move lever 32 to the position illustrated in FIGURE 2, that is, against the upper end of the slot 152 and in the rearmost of its positions along the longitudinal axis of the governor.

The end one of the balls of the ball-type chain 34 is secured to the lever 32 by means of a clip 156. During the pre-selection of the governing speed, in the manner above described, a lever 32 is rotated about the longitudinal axis of the governor and moved along the helical slot 152 so that the longitudinal position of that lever 32 is changed. If the selected speed is being increased, sleeve 146 is advanced to the left in the view of FIGURE 3. Conversely, upon the setting of a lower preselected governed speed, the sleeve 146 is moved to the right in that view. It will be appreciated that other means of adjusting the axial position of sleeve 146 or of adjusting the axial position of any counterpart of sleeve 146 may be employed.

The rotatable governor subassembly 158 comprises a spring 160, a clutch bushing 162, a valve bushing 164 and a pair of Weights 166 and 168. Rectangular apertures 170 and 172, the ends of which are generally arcuate, are formed near each end of the spring and a circular aperture 174 is formed medially of the spring. A pair of apertures 176 and 178 are formed along the longitudinal axis of the spring and intermediate the central aperture 174 and the two end apertures and 172, respectively. Element 160 is preferably of resilient material, and cadmium or zinc plated tempered spring steel has proved satisfactory in practice. In a constructed arrangement, the spring 160 was initially formed in the shape illustrated in FIG. 5 of the drawings and of stock about 0.002 inch in thickness of about of an inch in width.

To produce governor characteristics satisfactory for use in the system of FIG. 1, the spring 160 is preformed into a circle with the ends overlapping sufficiently to bring apertures 170 and 172 into alignment with one another. Spring 160 is illustrated in its preformed free position in FIG. 6 of the drawings.

The clutch bushing 162 is preferably formed of a wearresistant defiectable plastic, a polyamide resin commercially sold under the generic name nylon having proved to be satisfactory in use. Bushing 162 includes a centrally opertured head portion 180 (FIG. 6), a pair of diametrically opposed arcuate shoulders 182 and 184, a pair of diametrically opposed arcuate flanges 136 and 188 integral with shoulders 132 and 184 respectively, and a pair of diametrically opposed axially extending arcuate fingers 190 and 192. The inner surfaces of projecting fingers 190 and 192 define, in conjunction with the central aperture in head portion 180, a circular cylindrical surface the diameter of which is but slightly greater than the diameter of that portion of shaft 124 with which clutch bushing 162 is associated. Shoulders 182 and 184- have generally arcuate exterior surfaces so that they in combination define a generally rectangular element with arcuate ends similar in shape to the apertures 170 and 172 in the spring 160 (FIG. 5). Obviously, the length of the apertures 170 and 172 should be slightly greater than the diameter upon which shoulder surfaces 182 and 134 are formed in view of the curvature of spring 160. The flanges 186 and 188 cooperate with head portion 180 to retain the spring 160 in position upon the bushing 162 when the assembly is in place upon the shaft 124. However, the fact that flanges 136 and 188 are not continuous, coupled with the flexibility of the bushing 162 permits the bushing 162 to be inserted in the apertures 170 and 172 of the spring 160 during the assembly of the governor.

The valve bushing 164 is advantageously formed of the same material as the clutch bushing 162 and desirably has the same internal diameter. The head portion 194 of bushing 164 is provided with a generally conical recess so that the right-hand face of that bushing, in the view of FIG. 6. is in the form of a very thin annulus 9 serving as a valve surface 196 adapted to engage the face 156 of the sleeve 146 (FIG. 3) which serves as a valve seat. The projecting portion 198 (FIG. 6) of the bushing 164 extends through the aperture 174 in the spring 161).

Each of the weights 166 and 168 is in the general form of a segment of a right circular cylinder, the radius of the cylinder being less than the radius upon which the spring 1619 is preformed. In a constructed arrangement which produced a generator characteristic curve of satisfactory form, the radius of curvature of the major surfaces of weights 166 and 168 was about 0.196 inch whereas the radius of curvature to which the spring 160 was formed was in the order of of an inch, that is, in the constructed arrangement, the radius of curvature of the Weights was about 37% less than the radius to which the spring 160 was preformed. The chord 200 of the weight 166, for example, is below the diameter of the circle upon which the circular surface of the weight 166 is formed. Thus, in a constructed arrangement, the height of the weights was some 15% greater than the radius of curvature. The length of the weights 166 and 168, as illustrated in FIG. 4 of the drawings, is slightly greater than the width of the spring 166. While the radius of curvature of the weights 166 and 168 relative to the radius of curvature of spring 161) in its free position is significant, as will be described, to the output characteristics of the governor, the height and length of the weights control primarily only the mass of the weights and may be adjusted relative to one another as desired. In the illustrated form, the edges of each of the weights, as weight 166, are chamfered as at 202 and 204 to insure clearance between the weights and the bushings 164 and 162 respectively. To obtain a relatively large mass for the size of the weights, the weights 166 and 168 can be formed of lead. Each of those weights is provided with an upstanding stud which extends through the apertures 176 and 178 respectively, and is headed over as at 206 and 208, respectively, to secure the weights to the spring 166.

While the weights 166 and 168 are shown to be in engagement with the ends of fingers 190 and 192 in the view of FIGURE 6, when the sub-assembly 158 is placed in position upon the shaft 124 (FIG. 3), the spring 160 is deformed into a generally elliptical shape since, in the preferred arrangement, the distance between the righthand face of shoulder 128 on shaft 124 and the valve seat 150 is less than the distance between the faces of clutch bushing head 162 and of valve bushing head 164 when the sub-assembly 158 is in its free position as shown in FIG. 6. As a result of this deformation, the weights 166 and 168 are moved to the position shown in FIG. 3 of the drawings, in which they adequately clear the clutch bushing 162.

The compressing or deforming of the spring 160 into an elliptical shape effectively pre-stresses the spring 160 so that forces are exerting tending to move clutch bushing 162 to the left in the view of FIG. 3 and valve bushing 164 to the right. The former force tends to establish a driving relationship between the face of bushing 162 and the shoulder 128 so that the governor sub-assembly 158 will be forced to rotate with shaft 124. The latter of these forces tends to bring the face of valve bushing 164 into intimate engagement with the valve seat 150.

Since the chamber 212 defined by the bore of the extension 118 is connected to the outer air, or atmosphere, by a port 214 formed through the wall of the extension 118, that chamber will, under all operational conditions, be at the ambient air pressure. As was above noted in the discussion of the system of FIG. 1, the port 30, communicating with the chamber 116 (FIG. 3), is connected to a source of reduced air pressure and under normal operational conditions of the governor, chamber 111 will be at an air pressure less than the ambient air pressure. Consequently, with the unit at rest and with spring 160 exerting a substantial force tending to maintain valve bushing 164 against valve seat 150, a substantial pressure differential will exist between chambers and 212. The magnitude of this pressure differential will, of course, be determined by the extent of the pre-loading of spring 160 as manifested in the force by which valve bushing 164 is pressed into engagement with valve seat 151 In general, within limits, the pressure in cavity 110 will be equal to the ambient pressure in chamber 212 less the quotient of the spring force exerted upon the valve bushing 164, pressing it into engagement with valve seat 150, divided by the effective area of the valve. The eflective valve area is equal to the area of the circle defined by the inner surface of the valve lip 196 less the area the shaft 124 at the valve. The extent of this pre-loading, and hence the pressure within the cavity 110, may, of course, be adjusted, under both static and dynamic conditions, by rotating the lever 32 to shift the position of sleeve 146 and hence of valve seat 150. If the driver sets a higher controlled speed by shifting the position of knob 42 (FIG. 1) and advancing the sleeve 146 to the left (FIG. 3) obviously the spring 166 will be distorted into an ellipse having an even greater major axis and a lesser minor axis and the force pressing valve bushing 164 against valve seat will be increased.

When the vehicle is in motion, shaft 124 is rotated at a speed varying in accordance with the road speed of the vehicle. Centrifugal force acting upon the mass of the weights 166 and 168 will tend to displace those weights radially outwardly to an extent determined by the angular velocity of shaft 124. The effect of this movement of weights 166 and 168 is to tend to further deform spring so that the effect of the pre-loading of spring 160 is absorbed to a varying degree. Consequently, with any given static pre-loading of the valve 164, the force tending to maintain the valve in engagement with seat 150 decreases as a function of the angular velocity of shaft 124. Under normal operating conditions, 164 is not withdrawn from the valve seat 15!) adequately to permit cavity 116 to reach atmospheric pressure.

In the disclosed arrangement, the frictional force between the valve bushing 164 and the combination of the spring 160 and shaft 124 is greater than the frictional force between the bushing and the valve seat 150 so that the valve tends to rotate relative to the valve seat 150 upon rotation of the shaft 124, although the relationships may be such, if desired, that the valve 164 will not rotate relative to the seat 150. By using the noted plastic for the valve 164, no substantial wear has been detected even after extended testing of the unit, this being true even though the width of the lips on the valve 164, that is, the width of the annulus of contact between the valve 164 and the valve seat 150 was only fouror five-thousandths of an inch. While there is no great tendency for the valve seat to wear since the forces in the system are relatively small, it has been found to be advantageous to chrome plate the valve seat 150.

Just as the force tending to maintain valve bushing 104 in engagement with the valve seat 156 decreases with increasing rotational velocities of shaft 124, so does the force tending to maintain clutch bushing 162 in engagement with the face of shoulder 128 decrease with increasing road speed. This, of course, tends to reduce the frictional force between those elements and tends to permit clutch bushing 162 to slip with respect to shaft 124. Normally, however, no substantial slippage occurs, for as the force tending to maintain the face of head 148 of clutch bushing 162 (FIG. 6) against the shoulder 128 decreases, the force tending to deflect fingers and 192 towards one another and into tighter engagement with the shaft 124 increases. Consequently, the frictional driving relationship between the clutch bushing 162 and shaft 124 is maintained, the fingers 196 and 192 grasping the shaft more and more firmly as the frictional engagement between the head 180 and the shoulder 128 diminishes.

It will be observed, however, that it is desirable that bushing 162 serve as a clutch to accommodate transient rapid changes of angular velocity of the shaft 124 resulting, for example, from twisting and untwisting of the speedometer cable, and to this end the frictional force between clutch bushing 162 and shaft 124 is so selected that under these transient conditions the clutch will slip relative to the shaft.

If a conventional governor is utilized in the system of FIG. 1, the output pressure will tend to vary nonrectilinearly with veloctiy changes, the relationship approaching a second-degree curve such as that shown at curve 222 in FIG. 7 of the drawings. With the construction illustrated in FIGS. 2-4 of the drawings, the change in output pressure in response to changes in the velocity of rotation of shaft 124 approaches a rectilinear relationship as is illustrated in the representative curve 224 in FIG. 7 of the drawings, permitting a wider range of control than is feasible with conventional governors. Curve 224, of course, represents the relationships at but one setting of the adjusting knob 42, that is, at one preselected governed road speed of the vehicle. The pressure-velocity curves at other settings of the unit will tend to be generally parallel to but spaced from curve 224.

While an explanation of the physical phenomena causing the illustrated governor to produce the indicated output characteristic has not been definitively established, it is the present best theory that these desirable characteristics arise from both the preforming and the nature of the preforming of the spring 16-8 and from the disparity between the radii of curvature of the spring 169 and of the weights 165 and 163. Each quarter of the spring 160 may be viewed, for analysis, as in the nature of a cantilever-mounted single-leaved spring. Viewing the upper right-hand quarter of spring 160 in the view of FIG. 3, the effective length of that spring is from the point of support of the spring upon the shaft 124 to the point of engagement of the spring with the weight 166. If that spring section acts as a cantilever mounted rectangular-leaved spring, then the extent of its deflection varies in proportion to the force applied thereon and as a function of the third power of the length. It seems clear that whether the spring does conform to this relationship or not, the amount of deflection certainly varies with varying force and, in some relationships, with varying effective lengths. As weight 166 moves outwardly, the portion of the total length of this section of spring 16% (and the other sections act correspondingly) which is in engagement with the curved surface of weight 166 incrementally increases so that the effective length of this section of spring 160, that is, the portion of this spring section which is capable thereafter of deflecting, is progressively decreased. In other words, due to the progressive effective shortening of each of the four constituent sections of spring 112, the effective stiffness of the spring increases with increasing rotational velocities so that the force required to produce the next increment of movement is greater that it was for the preceding increment of motion.

Reference may be made to the above-noted copending applications, the disclosures of which are incorporated herein by reference, for a further discussion of the nature and characteristics of the governor and for a discussion of modifications of the above-described governor structure, one of which will be discussed hereinafter.

In the initial assembly of the governor 24 to the vehicle, the governor body is assembled to the speedometer at an appropriate rotational angle, such as, for example, with the lever 32 approximately perpendicular to the line of the chain 34. Thereafter, final adjustment is made either by changing the effective length of the chain 34 or by changing the rotational position of the knob 42 relative to its shaft, or both.

The pressure controller 56 and the control valve 50, diagrammatically represented in the system of FIG. 1, are presented in more detail in FIG. 8 of the drawings. In the representatively disclosed arrangement, the control valve and the pressure controller are shown formed with a unitary housing casting 239. The pressure controller portion of the housing includes a port 240 which is connectable to the source 23 of reduced air pressure. It is assumed that the source of reduced pressure with which the pressure controller is associated is capable of maintaining a pressure of eleven pounds per square inch absolute or lower under normal conditions, that is, during idling of the engine or during traveling at normal cruising speeds. It will be appreciated that in customary internal combustion engines the absolute pressure in the intake manifold tends to rise above this value and approach atmospheric pressure when the throttle of the vehicle is rapidly depressed to its full open position, particularly when the road speed of the vehicle is low. Under those circumstances the pressure at port 240 rises above the assumed valve so that the pressure controller is unable to maintain the assumed controlled pressure, but advantage is taken of this fact to produce a desirable operational characteristic as will be noted.

The cavity 242 is defined by a portion of the housing 239, by a valve 244 and by a diaphragm 246. The periphery of the diaphragm 246 is sandwiched between an annular surface of the housing and a flange on the cover 248, the cover 248 being secured in place by crimping edges of the body into overlying relationship with the flange thereon. The diaphragm 246 is centrally apertured to accept a projecting tubular portion 250 of a nut 252. The projection 250 is crimped tightly to retain a pair of washers 254 and 256 in place on opposite sides of the diaphragm 246. The internally threaded nut 252 accepts the threaded valve stem 258 which carries the ball valve 244 and supports it in position to engage the valve seat 262. A compression spring 262 operates between a spring seat formed on the housing 239 and the adjacent face of the washer 254 so as to exert a continuing force tending to move the diaphragm in a direction to move the ball valve 244 from its seat 260.

The cover 248 is provided with a central aperture into which a plug 264 is fitted. The plug 264 is provided with a small aperture so that the cavity, defined by the diaphragm 246 and the cover 248, communicates with the atmosphere and hence remains at atmospheric pressure. The end of the valve stem 258 nearest the plug 264 is slotted so that, upon removal of the plug 264, a screwdriver may be inserted through the aperture in the cover 248 and into engagement with the valve stem to rotate that stem relative to the nut 252 to adjust the distance between the ball valve 244 and the diaphragm 246 so as to change the preload height of spring 262 and to adjust the controlled pressure in cavity 242.

As will be seen, the cavity 242 is connected, through restricted and metering orifices to the atmosphere so that the pressure within the cavity 242 tends to rise towards the atmospheric value. The ball valve 244 will consequently open from and close to its seat 260 alternately to connect and disconnect the port 240, with its source of low pressure, to the cavity 242, tending to maintain the cavity 242 at a controlled value under steady operational conditions of the vehicle. As will be discussed in detail hereinafter, with the illustrated unbalanced pressure controller, the controlled pressure, as applied to the control valve chamber or cavity 60, is varied as a preselected function of the variations of the pressure of the intake manifold, to provide, in cooperation with other elements of the system, a degenerative feedback action, as will be described hereinafter.

It has been found that the operational characteristics of the system can be improved by reducing the area of contact between the ball and seat in the pressure controller and the control valve, as by seating the ball against a radiused corner (as in another embodiment to be described) or an angle seat rather than by employing the illustrated spherical seats.

Control valve 50 includes chambers 58 and 60 demarked by diaphragm 64, chamber 58 being connected to the governor 24 by tube 48 and chamber 60 being connected to pressure controller 56 through orifice 54. The diaphragm 64 is trapped between the housing or body 239 and the cover 266 and carries a valve assembly formed similarly to that of the pressure controller 56. Thus, nut 288 includes a projection which extends through an aperture in diaphragm 64 and is crimped over to secure washers 290 and 292 in place on opposite sides of the diaphragm 64. The threaded valve stem 224, carries the ball valve 70 and threadedly engages the nut 238. It is preferred that the axial position of the valve stem 94 with respect to the nut 288 be established during the course of manufacture, but if desired provision may be made for subsequent adjustment similar to that described in connection with the regulator 56, as is illustrated in part by the slotting of the head of screw 294. The valve seat 72 is a part of a bushing 296 which is press fitted or otherwise secured in an extension of the housing 239. It will be noted that the valve seat is fixed with respect to the vehicle and is not connected to and does not move with the throttle 13. It has been found that improved operational characteristics accrue if the area of contact between the ball and seat is reduced over that shown, as by seating the ball against a radiused corner or an angle seat, as above noted in connection with the pressure controller. A compression spring 298 operates between a face of the housing 239 and the washer 290 and tends to maintain ball valve 70 seated against its seat 72.

The diaphragm and valve assembly differs from that utilized in the pressure controller 56 in that an orifice 66 is established interconnecting the control valve cavity 60 and the surge cavity 58. In a constructed embodiment, this orifice had a diameter of about 0.030 inch and was established by drilling a hole somewhat larger than that through the washers 290 and 292 and through the diaphragm 64 and inserting a roll pin or the like therethrough having the desired internal diameter. The roll pin not only establishes an orifice of appropriate size but also insures alignment of the holes in washers 290 and 292 and diaphragm 64 and prevents reduction in the size of orifice 66 as a result, for example, of swelling of diaphragm 64.

The end of the valve stem 294 extends within a cavity 300 in a vent valve 302 which cooperates with a valve seat 304 formed integrally with the body 239. Vent valve 302 controls the communication between the control valve cavity 62 and a cavity 306 which is in communication with the atmosphere through a filter 308.

The vent valve 302 is slidably supported by the bushing 296 by virtue of the provision of three spaced-apart longitudinal fins 310, 312 and 314 (FIG. 9) the outer surfaces of which lie in a cylinder having a diameter approximately equal to the internal diameter of the bushing 296.

The valve stem 294 does not engage the vent valve 302 but is adapted to move within the bore 300 in that valve. However, a spring 316 acts in compression between a spring seat formed by a shoulder of the bore 300 and the adjacent surface of the ball valve 70, acting to force the vent valve 302 away from the ball valve 70 and hence into engagement with valve seat 304. Consequently, chamber 62 is selectively connectable with chamber 60 under the control of ball valve 70 and is selectively connectable to the atmospheric pressure, as it l 4 appears in cavity 306, under the control of vent valve 302.

It is to be understood that valve 302 is not an imperative element of the combination but does serve a useful function as a relief valve under certain circumstances to be described. The output port 52, connected to the cavity 62, is connected to the servo cylinder as noted in connection with the description of FIG. 1.

The air pressure acting upon the lower surface of diaphragm or pressure sensing device or actuating means 64 produces a force tending to seat the ball 70. The opposing force acting on the other side of the diaphragm 64 and tending to unseat the ball valve 70 is, of course, determined by the governor output pressure. In a first constructed arrangement, the spring 293 was selected to exert a force in a direction to seat the valve 70 of about one and one-half pounds, which is small relative to the force exerted on diaphragm 64 by the pressure in chamber 60. With both valve 70 and valve 302 on their seats, the vent spring 316 exerts a small force (e.g., 0.05 pound) tending to maintain both valves on their seats.

As was previously described with reference to FIG. 1 of the drawings, when the velocity of the vehicle is below the governed speed, chamber 62 is at about atmospheric pressure. As a result there is a force acting in a direction tending to close the valve '70 equal to the product of this pressure times the area of the aperture which is closed by the valve. Similarly, there is a force exerted upon the valve 70 in a direction tending to open that valve equal to the pressure in the chamber 60 times the effective area of the valve 70 upon which that pressure can act.

The pressure established by pressure controller 56 and the characteristics of the governor are selected so that the governor will produce a selected range of pressure variations in the control valve chamber 58 over the desired range of vehicle road speeds. The other system parameters are then selected so that the resultant force on the valve 70 will reverse direction, at each setting of the governor, at some point in the range of pressure variations in the chamber 58. Thus, the curve 224 illustrated in FIG. 7 shows the pressure variation at the governor and hence at the control valve chamber 58 with variations in road speed from 25 to 65 miles an hour for a governor setting of 50 miles per hour, curve 224 representing, as above noted, but one of a large family of approximately parallel curves. In practice, it has been found to be desirable to have this change of direction of resultant force occur a few miles an hour below the controlled speed, e.g., for a controlled speed of 50 miles an hour, the cross-over may occur at about 46 to 47 miles per hour. Below that speed, the pressure in chamber 58 is lower than the critical value so that the valve 70 is maintained upon its seat 72. It will be observed that the spring 316 opposes the movement of the ball 70 in its unseating direction with an increasing force the further the ball 70 moves from its seat, and in the above noted first constructed arrangement, the spring force increased from about 0.05 pound with the ball 70 fully seated to about 0.3 pound when the ball was fully unseated.

Below the set speed, with the valve 70 closed, there is pressure equality between the two chambers 92 and 93 of the cylinder 80 (FIG. 1). As the velocity of the vehicle is increased by depressing the throttle 22 to open the carburetor 16, the slack in the chain 102 is taken up, and the piston is or may be (depending upon the initial position of piston 90) moved to the left. If this movement is not abrupt, effective pressure equilibrium will be maintained by virtue of the flow of air through orifice 100. If the throttle 22 is changed in position abruptly, so that piston 90 is drawn to the left abruptly, the size of the orifice may not be adequate to establish equilibrium rapidly enough so that the action of the piston will not be detected. If in any given design the cylinder 8h does tend to aifect the motion of the throttle 22 in the range of road speeds below the selected road speed, the condition can be avoided, if desired, by the provision of the vent valve 392 which is set to open (assuming the control valve 70 to be closed) whenever the pressure in chamber 62 and hence in chamber 8 is, for example, one pound per square inch below atmospheric pressure. The opening of vent valve 302 establishes pressure equilibrium on the two sides of the piston head 90 thereby preventing that piston from having any detectably significant effect upon the movement of throttle 22 below the controlled speed.

When the automobiles velocity has been increased to the controlled value, control valve 70 is opened to establish communication between the chamber 60 in the control valve 50 and the cylinder chamber 98 via the tubing 76 and the chamber 62. As a result, in the noted first constructed arrangement, a pressure differential in the order of three and a half pounds per square inch will tend to exist across the piston head 90. However, if the position of the throttle 22 is correct for that speed so that there is no further tendency for the car to increase in road velocity, the air flow from the atmosphere through cylinder chamber 92, orifice itlt), chamber 98 past the control valve 70 and through the pressure controller will tend to reduce this pressure differential by raising the pressure in chamber 98 and hence in chambers 62 and 6%. Any increase of pressure in chamber 60 above the selected value will, of course, tend to result in the closure of valve 70 so that with the throttle 22 in the correct position for that road speed the valve 70 will be in an incipiently opening and closing condition and the pressure differential across the piston head 90 will not be such as to force the throttle 22 away from its selected position. However, in order for the throttle 22 to be moved in a direction to increase the velocity of movement of the automobile above the governed velocity, the piston head 9% must be moved to the left. This leftward movement of piston head 90 will result in a transient reduction in the pressure in the cylinder chamber so that the piston 96 will transiently oppose that advance of the throttle 22. It will be observed, however, that this system will not prevent such movement of the throttle 22 but will only add a force to that of spring 164 making it more difficult for the operator to advance the throttle 22 beyond the appropriate position for the set governed speed.

If the operator advances the throttle despite the transient opposing force in an effort to increase the road speed of the vehicle above the set value, the pressure in control valve chamber 58 will rise and the ball valve 7%) will be further opened, reducing the pressure differential between chambers 60 and 62 and producing a pressure in cylinder chamber 98 which is less than that in chamber 92 and which remains less since the velocity of air flow through the orifice 100 is not adequate to establish pressure equality under these conditions. As a result, a force is exerted aiding that of spring 1M tending to move the throttle 22 to its released position. The magnitude of this force may be selected in design at any appropriate value, with an increased force in the order of four to six pounds being found to be satisfactory in practice. The operator may cause the vehicle to move at a velocity greater than the controlled rate, but he will have to exert a preselected amount of additional force upon the throttle 22 to maintain the vehicle at that increased rate. If the operator does not maintain the requisite additional force, the throttle 22 will move towards its released position until the velocity of the vehicle has again reached the set value.

With the vehicle traveling above the set speed so that valve 70 tends to be open, the force exerted by spring 316 in the vent valve 302 is increased so as to prevent the vent valve from opening the vent even though the pressure in chamber 62 falls substantially more than one pound per square inch below atmospheric pressure. In

practice, the increase in spring force is such that vent valve 302 will not open, with ball valve 76 open, unless the pressure differential is in the order of six pounds per square inch. Therefore, if the operator depresses the throttle 22 abruptly, so as rapidly to move piston head 90 to the left and create an additional pressure reduction in chamber 98 and hence in chamber 62, vent valve 302 may open, establishing an upper limit to the total additional force which the driver must apply to override the governing system.

Since the intake manifold absolute pressure in an internal combustion engine rises toward atmospheric if the throttle is advanced to its full open position at relatively low road speeds, it will be observed that the governing system cannot only be overridden if the need arises, but in an emergency situation in which the driver advances the throttle 22 to its full open position, that increase in absolute manifold pressure will close valve 70 to effectively transiently disable the governing system so that effectively no force additional to that provided by spring 164 is required to maintain the throttle 22 at its full open position to permit rapid acceleration of the vehicle.

Curve 322 in FIG. 7 of the drawings, which is based upon the above noted first constructed arrangement, illustrates the changes that occur in the pressure in chamber 98 of cylinder with changes in road speed, assuming that the throttle 22 is not moved abruptly. In the representatively disclosed arrangement, a pressure differential begins to exist between the two sides of the piston at a speed several miles an hour below the selected speed. For example, with a set speed of 50 miles an hour, a detectable pressure differential may begin to exist at a speed as low as 45 miles per hour, although this is a design consideration which may be readily modified.

The governing system has been found to be highly useful in the driving of vehicles on modern limited-access freeway and turnpike driving. The driver may manually set the governor to the established speed limit or to any other selected value and rest the weight of his foot upon the accelerator pedal so that the force applied to the throttle exceeds that necessary to overcome the throttle return spring 104 but is less than the sum of the force of that spring and the additional force imposed by the cylinder 80. The vehicle, assuming proper calibration of the system, will assume the selected speed and there remain, with the operator of the vehicle being able to vary the pressure of his foot upon the throttle within substantial limits without changing the velocity of the vehicle. It has been found that as the vehicle goes down grade and tends to pick up seed, the throttle will detectably move upwardly, moving the drivers foot therewith, to maintain the vehicle speed at the selected value, and, conversely, when the vehicles road speed tends to fall during ascent of a hill, the throttle may be felt to move downwardly under the relatively constant force exerted by the operator to again maintain the vehicle at the selected speed.

It 'will be observed from the foregoing that the governing or speed sensing means or speed transducer assembly 24 is connected to the speedometer cable or rotatable element 14 to sense the velocity of rotation thereof, constituting an actual vehicle or unit speed input to the governor or transducer assembly 24. The output signal produced by the sensing means is controlled by the manually settable means including the knob 42 by means of which the nominal controlled velocity of rotation of the speedometer cable 14 is selected which, of course, is reflected as a nominal controlled velocity of the vehicle or engine. The adjustment of the governor or transducer 24 by the knob 42 constitutes a selective desired speed input thereto. When the sensed velocity of rotation of element 14 is the same as the nominal controlled velocity of rotation of element 14 as selected by the means including knob 42, i.e. when the vehicle is traveling at the selected road speed in the illustrated arrangement, the governor produces a preselected output signal, represented, in the illustrated embodiment, by a preselected fluid pressure in chamber 58. When the sensed velocity of rotation of element 14 diifers from the selected nominal controlled velocity of rotation of that element, over a preselected range of such variations, the output or error signal varies in accordance with the direction and magnitude of that difference, as is illustrated, for example, in curve 224 in FIG. 7 (and in the governor curve of FIG. 25, to be discussed).

Thus, the speed sensing governor 24 varies the average differential fluid pressure which is applied to the control valve 54) effectively as a continuous function of the magnitude of the deviation of the rotational velocity of the rotatable element 14 from the selected velocity over a range of such variations. As above noted, and as is illustrated in curve 224 in FIG. 7 (and similarly in the governor-pressure curve of FIG. 25, to be discussed hereinafter), the relationship is eifectively rectilinear over a range of variation for any given selected speed, that is, the output of the governor or speed sensing means is effectively proportional to the speed change in that range and the governor or transducer produces a continuously variable proportional control speed error signal throughout the range or zone of proportional speed control. Similarly, the control valve is efiective, over a range, to vary the pressure applied to the servo or actuator chamber 93 in accordance with the air-pressure-diiferential applied to the valve by the governor, as is illustrated, for example, in FIGS. 7 and 25.

However, if the sensed speed is sufficiently below the set speed, the output signal of the governor 24 reaches a value at which the valve 70 is and remains closed, an nnderspeed error signal output, and conversely when the vehicle is traveling sufliciently above the set speed, the output signal from governor 24 changes to a value at which the control valve 70* tends to remain fully open, an overspeed error signal output, as above discussed and as illustrated in FIG. 7 of the drawings. The control valve, of course, changes the effective fluid pressure in the servo chamber 98 in direction and magnitude from a selected fluid pressure (such as the above indicated three and one half lbs. per square inch) in accordance with the changes of that output signal from the preselected value thereof. When the valve is fully closed, chamber 98 is disconnected from the source of vacuum and hence rises to atmospheric value, as a limit, and conversely, when the valve 70' is wide open, there is a maximum reduction of pressure below atmospheric value in chamber 93, .to a limit value, commensurate with the intake manifold pressure conditions. Thus the governor or speed transducer assembly 24 establishes a controlled speed magnitude zone of proportional speed which is of less speed magnitude than the magnitude of the speed unit or vehicle variation and, in fact, as indicated elsewhere herein, the preferred Zone of proportional speed is in the order of a few miles an hour to each side of the selected or unit speed input and is substantially centered thereon, that is, the range of effective control extends to each side of the selected speed. Of course, the control speed magnitude shifts as the selected speed is changed.

The apparatus including the control valve or pressure control valve assembly 50, the servo or pressure unit motor zone 80 and the interconnecting tube 76 may be considered to constitute a unit or vehicle speed control mechanism which is connected to the governor or speed transducer assembly 24 to receive and respond to the signal output of that governor as it appears in chamber 58. That unit speed control mechanism has two different pressure inputs, one being the vacuum input to chamber 60 at the outlet of passage 54, for example, and the other being an atmospheric pressure input via orifice 100, for example. The output pressure of the unit speed control mechanism appears at chamber 98 and, as above discussed, varies as a function of the proportional speed error signal appearing in chamber 58. In the controlled speed magnitude zone of proportional speed, the output pressure in chamber 98 is intermediate and continuously variable between those two (vacuum and atmospheric) pressure inputs when the proportional control speed error signal appears at chamber 58. See FIGS. 7 and 25. As noted, when the overspeed error signal is received, valve 79, which serves as 43. proportional control mechanism, is fully unseated from valve seat 72, that is, it is at a fully open limit condition, so that the pressure in chamber 98 is substantially equal to the source of pressure at the outlet of passage 54 and when the overspeed error signal is received at chamber 58, valve 70 is effectively fully closed, that is, at its fully closed limit condition, so that the pressure in chamber 98 is equal or substantially equal to atmospheric. It will be observed that the proportional control speed error signal appearing at chamber 58 differs from the underspeed error sigial in one sense or direction, and that the overspeed error signal difiers in magnitude from the proportional error signal in that same sense, that is, in the same direction. The servo or motor 8%) includes a piston which is responsive to the pressure in chamber 98 and is, as illustrated, adapted to be connected with the unit speed controller 18 by linkage 102.

An improved system is illustrated in FIGS. 10-24 of the drawings. In addition to other features, this improved system has the capability not only of controlling the vehicle semi-automatically, in a manner similar to that above discussed with the system of FIG. 1, but also of controlling the vehicle on a fully automatic basis in which the driver does not need to exert any force on the accelerator pedal to control the speed of the vehicle.

in general, the system of FIGS. 10-24 comprises a rotationalspeed-responsive pressure modulating valve (FIGS. 10-12) driven by the vehicles speedometer cable, a manual controller (FIGS. 13, 14) for setting the control speed of the governing arrangement of FIGS. 10-12 as well as for controlling whether the system will or will not be placed in operation and whether the operation will be on a semi-automatic or a fully-automatic basis, a pressure controller and control valve assembly (FIGS. 15-17) which is coupled to the intake manifold of the internal combustion engine of the vehicle and which is controlled by the governing arrangement of FIGS. 10-12 and by the manual controller of FIGS. 13 and 14, and which, in turn, controls a servo (FIGS. 18-24) which is coupled to the throttle and accelerator pedal of the automobile and which is capable of exerting a unidirectional force thereon during semi-automatic or speed warning operation (as in the previously described arrangement) and capable of bidirectionally applying forces thereto during tiull automatic operation. The system operates as a speed control system in both cases, being specifically characterizable as a speed warning control system in the semiautomatic mode of operation and as a speed maintaining control system in the fully-automatic mode of operation.

In semi-automatic operation, the governing arrange. ment of FIGS. 10-12 modulates air pressure in accordance with the deviations of the road speed of the vehicle (as reflected in the rotational speed of the speedometer cable) from the preselected value as set by the manual controller of FIGS. 13 and 14. This modulated air pressure is applied to the assembly of FIGS. 15-17 on a fluiddynamic basis to control the magnitude of the pressure differential applied to the servo of FIGS. 18-24 and thereby to control the reactive force applied against the drivers foot. This reactive force will first be applied as the vehicle approaches the selected road speed and will thereafter oppose any eifort of the driver to depress the accelerator pedal beyond the position necessary to maintain the selected road speed. As in the system of FIG. 1, the reactive force applied to the drivers foot will be modulated over a range as necessary to compensate for varying foot pressures applied by various drivers. In the event that the driver wishes or needs to accelerate rapidly beyond the set speed, he may 'do so without efiectively 

1. IN A VEHICLE, THE COMBINATION OF AN INTERNAL COMBUSTION ENGINE HAVING A THROTTLE AND A SOURCE OF AIR WHICH CHANGES IN PRESSURE AS A RESULT OF MOVEMENT OF SAID THROTTLE PRIOR TO THE CHANGE OF OUTPUT TORQUE OF THE ENGINE WHICH RESULTS FROM THE MOVEMENT OF SAID THROTTLE, AND ROAD SPEED STABILIZING MEANS COMPRISING CONTROL MEANS RESPONSIVE TO SAID CHANGES IN PRESSURE IN EITHER DIRECTION AND EFFECTIVE INDEPENDENTLY OF ANY CHANGE OF ROAD SPEED AND INDEPENDENTLY OF ANY CHANGE OF ROAD LOAD OF SAID VEHICLE, AND MEANS CONTROLLED BY SAID CONTROL MEANS FOR MOVING SAID THROTTLE TO CHANGE SAID PRESSURE IN THE OPPOSITE DIRECTION. 